Atherosclerotic coronary heart disease (CHD) is the number one public health problem in the United States. CHD has been increasing in prevalence and with the aging of the baby boomers and the increase in major cardiovascular risk factors in the population (smoking, obesity, and physical inactivity) over the last 10 years the problem will be even worse in the 21st century. This is not just a U.S. problem, but is occurring world wide. The WHO has recently predicted that by 2020 heart disease will replace infectious disease world wide as the number one cause of disability expressed as years of healthy life lost to death or disease. CHD is a complex genetic disease with many genes involved and important gene-environment interactions. In this proposal we will use the facilities of the Rockefeller Hospital GCRC to identify and study genes and gene-diet interactions that are important in determining CHD susceptibility.